This invention relates to a piston for two-cycle engines and more particularly to an improved arrangement for cooling the pistons of a two-cycle internal combustion engine.
As is well known, the problem of heat dissipation is a particularly important one in connection with internal combustion engines. The piston and particularly its head is one of the more highly heated components of the engine. It is essential that the heat that is transmitted to the head of the piston can be effectively dissipated so as to avoid overheating of the piston. This problem is particularly acute since the piston is not in any significant direct contact with the cylinder bore which, itself, normally is provided with its own cooling system. As a result, heat must be transferred from the piston to the cylinder bore for dissipation through the piston rings. Also, the lubricating system of a four-cycle engine may be employed for cooling the piston during engine operation.
It should be obvious that unless the piston is adequately cooled, in addition to the possibility of piston burning, there becomes the likelihood that the highly heated piston can deform and bind in the cylinder bore. The problems of heat dissipation in two-cycle internal combustion engines are particularly acute. Because the intake and exhaust ports are normally formed by openings in the cylinder wall, the area of contact between the piston rings and cylinder wall are greatly reduced. Also, with a two-cycle engine, the exhaust gases in the exhaust port also contact the piston during times when the exhaust port is closed and thus can further add to the head loading on the piston.
Because of the heat loading on pistons in two-cycle engines and the particular problems attendant therewith, the configuration and the shape of the piston in these engines is even more critical than with a four-cycle engine. In addition to the heat dissipation problems aforenoted, there is also the question of insuring good sealing by the piston rings under varying heat conditions and also the concern that the piston rings may become lodged with carbon due to high heat and improper heat dissipation.
It is, therefore, a principal object of this invention to provide an improved arrangement for cooling the piston of an engine.
It is a further object of this invention to provide an arrangement for cooling the piston of a two-cycle internal combustion engine.
It is a still further object of this invention to provide an arrangement for cooling a two-cycle piston by providing a flow of air across the piston even at the time when the ports of the engine are closed.